Updated from 8:53 a.m. EDT

Shares in

Mylan Laboratories

(MYL) - Get Report

plunged Wednesday after the company said it will sue the Food and Drug Administration over the approval of a pain relief drug and suspended annual earnings guidance as a result.

Shares fell $2.27, or 10.2%, to $22.15.

The Pittsburgh-based drugmaker said the lawsuit will seek to restore final approval for its fentanyl transdermal system on the grounds that the FDA had "acted contrary" to two U.S. laws, its published regulations and the legal precedent.

At issue is Mylan's efforts to sell a generic version of Duragesic, a pain relief patch marketed by Janssen Pharmaceuticals, a unit of

Johnson & Johnson

(JNJ) - Get Report

. Janssen Tuesday reportedly said the FDA had granted additional patent protection, delaying the introduction of Mylan's product by another six months.

"We view this decision as yet another assault on the generic pharmaceutical industry," the company said in a statement.

The company said that because of a hearing in the lawsuit to be held sometime before July 23, it had decided to suspend full-year guidance. In May, the company forecast earnings of $1.30 to $1.40 a share.Analysts expect the company to earn 26 cents in the quarter and $1.35 for its fiscal year ending in March 2005.